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CD2 can mediate TCR/CD3-independent T cell activation
H Ohno1, C Ushiyama, M Taniguchi
1Division of Molecular Genetics, School of Medicine, Chiba University, Japan.
Journal of Immunology (Baltimore, Md. : 1950)
|June 1, 1991
Summary
T cells can be activated by CD2 molecule signaling independently of the T cell receptor (TCR)/CD3 complex. High CD2 expression is crucial for this activation in TCR/CD3-negative cells.
Area of Science:
- Immunology
- Cell Biology
Background:
- T lymphocyte activation is primarily mediated through the T cell receptor (TCR)/CD3 complex.
- Polyclonal T cell activation can also occur via the CD2 molecule, but its dependence on TCR/CD3 signaling has been debated.
Purpose of the Study:
- To investigate whether CD2-mediated T cell activation requires TCR/CD3 expression or signaling.
- To resolve the controversy surrounding the role of TCR/CD3 in CD2-induced T cell responses.
Main Methods:
- Utilized CD2-transfected, TCR/CD3 surface membrane-negative human and mouse T cell lines.
- Assessed interleukin-2 (IL-2) secretion and intracellular calcium (Ca2+) flux as indicators of T cell activation.
Main Results:
- CD2-mediated IL-2 secretion and Ca2+ increases were observed in TCR/CD3-negative T cells.
- High levels of CD2 expression and a critical threshold were necessary for activation in the absence of CD3.
- Co-expression of TCR/CD3 complex significantly reduced the CD2 expression threshold for activation.
Conclusions:
- CD2-mediated T cell activation can occur independently of surface TCR/CD3 expression.
- A threshold of CD2 expression is critical for activation in TCR/CD3-negative cells.
- CD2 may play a role in the activation of T cells lacking TCR/CD3 complexes.